advent.ts

import { piped } from "remeda";
import z from "zod";

const getBlocks = piped(
    (a: string) => a.split(""),
    (a) =>
        a.map((char, index) => {
            const isEven = index % 2 === 0;

            const charValue = z.number().parse(+char);
            if (isEven) {
                return {
                    type: "file",
                    id: index / 2,
                    size: charValue,
                } as const;
            } else {
                return {
                    type: "space",
                    size: charValue,
                } as const;
            }
        }),
    (a) =>
        a.reduce(
            (acc, el) =>
                acc + (el.type === "file"
                    ? el.id.toString().repeat(el.size)
                    : ".".repeat(el.size)),
            "",
        ),
);

const isBlockDone = (block: string[]) => {
    let hitFree = false;
    for (const el of block) {
        if (el === ".") {
            hitFree = true;
        }
        if (hitFree && el !== "." && el !== "0") {
            return false;
        }
    }
    return true;
};

const reorgBlock = piped(
    (a: string[]): string[] => {
        if (isBlockDone(a)) return a;

        const clone = structuredClone(a);
        while (true) {
            // console.log(clone.join(""));
            if (isBlockDone(clone)) {
                break;
            }
            const firstDotIndex = clone.findIndex((n) =>
                n === "."
            );
            const lastLetterIndex = clone.findLastIndex((
                n,
            ) => n !== "." && n !== "0");

            clone[firstDotIndex] = clone[lastLetterIndex];
            clone[lastLetterIndex] = ".";
        }

        return clone;
    },
);

const getChecksum = piped(
    (input: string[]) =>
        input.filter((n) => n !== ".").map((n) =>
            z.coerce.number().parse(n)
        ),
    (n) => n.reduce((acc, curr, i) => acc + curr * i, 0),
);

const solution = piped(
    getBlocks,
    (n) => n.split(""),
    reorgBlock,
    // (n) => n.join(""),
    getChecksum,
);